From British Patent, GB 2 145 033 Ba a binding apparatus is known for binding loose sheets of paper or the like to form a booklet. For this purpose, a U-shaped channel is inserted in the binding apparatus such that the channel opening points to the side, enabling the stack of sheets needing to be bound to be introduced into this channel opening. Then a pressure applying device is pressed onto the upper side of the channel, causing the channel to be compressed such that the sheets are clenched between, and securely held by, the two channel legs. With such binding apparatus it is possible to obtain a stable booklet in a relatively simple manner. However, this binding apparatus is only suitable for use with books or channels of a particular size. The deformation of wider or narrower channels is subject to restrictions, an optimum deformation being however not possible.